This invention relates to an automatic stepless transmission apparatus and method, and particularly to such transmission and method which changes a rotational speed ratio of an output/input shaft automatically in response to the load of the output shaft and the rotational input of the input shaft without any clutch and removal or replacement of gear, and which can be utilized in any mechanical device requiring the change of gears between a prime mover and load.
The method of the invention can be described as a method of automatic adjustment of a variation ratio for distributing the input rotational force into a low speed power line having low variation ratio and a high speed power line having high variation ratio, and for combining the two power lines again to allow stepless variation. The method is characterized in that the rotational force of the low speed power line is brought into balance with the rotational force of the high speed power line by applying rotational resistance which impedes the rotational force of the low speed power line. The rotational resistance varies according to the phase between the input shaft and the output shaft of the load detecting gear set. The rotational resistance applied to the low speed power line is decreased upon an increase of the load or a decrease of the input power and increased upon decrease of the load or increase of the input power, such that the variation ratio is automatically adjusted depending on condition of the input and the load.
A rotational force adjusting device which utilizes a differential gear assembly, having a sun gear, a planetary gear, a ring gear and a planetary gear carrier, is characterized in that a lever is provided around the planetary gear carrier. The position of the lever is set by a position setting means, including a spring, such that the spring force is applied both to the sun gear 704 and to the ring gear 705 which are under rotation.
The prior art described in U.S. Pat. No. 4,598,610 discloses a complicated device which is of little practical use due to its uncertainty in automatic control and power transmission.
Therefore, it is an object of this invention to solve the problems of the prior art devices and to provide an improved automatic stepless transmission apparatus which is not complicated as those in the prior art and which has reliable speed control operation, efficient power transmission and rapid action against variation of load.
It is another object of this invention to provide an improved method for transmitting rotational power steplessly with a gear assembly, and automatically in response to variation of load.
It is another object of this invention to provide a rotational force adjusting device which imposes a rotational resistance on a sun gear rotating at one speed and which adds a rotational force of almost the same magnitude as the rotational resistance imposed on the sun gear, to the ring gear rotating in a direction opposite to the sun gear.